Configuration and viewing display for an integrated model predictive control and optimizer function block

Abstract

An interface or display routine is provided for use in viewing and configuring a function block that performs integrated optimization and control within a process control system. The interface routine may enable a user to view or configure variables, values or other parameters associated with the integrated optimization and control block within the process control system. For example, the interface routine may display the current operating state of the integrated function block, may enable a user to select inputs and output of the function block for use in providing integrated optimization and control, may enable a user to select a particular or desired optimization function for use in the function block, etc. The interface routine may also display the multiple input output curves associated with the optimizer and the controller sections of the integrated function block in a manner that provides ease of view and selection of these curves as part of the algorithm used by the integrated function block.

Description

RELATED APPLICATION[0001]The application is a continuation application of and claims priority from U.S. patent application Ser. No. 10 / 241,350, entitled “Integrated Model Predictive Control and Optimization within a Process Control System,” which was filed on Sep. 11, 2002.FIELD OF THE INVENTION[0002]The present invention relates generally to process control systems and, more particularly, to the use of an optimized model predictive controller within a process control system.DESCRIPTION OF THE RELATED ART[0003]Process control systems, such as distributed or scalable process control systems like those used in chemical, petroleum or other processes, typically include one or more process controllers communicatively coupled to each other, to at least one host or operator workstation and to one or more field devices via analog, digital or combined analog / digital buses. The field devices, which may be, for example valves, valve positioners, switches and transmitters (e.g., temperature, pr...

AI Technical Summary

Benefits of technology

[0012]An interface or display routine is provided for use in viewing and configuring a function block that performs integrated optimization and control within a process control system. The interface routine may enable a user to view or configure variables, values or other parameters associated with the integrated optimization and control block within the process control system. For example, the interface routine may display the current operating state of the integrated function block, may enable a user to select inputs and output of the function block for use in providing integrated optimization and control, may enable a user to select a particular or desired optimization function for use in the function block, etc. The interface routine may also display the multiple input output curves associated with the optimizer and the controller sections of the integrated function block in a manner that provides ease of view and selection of these curves as part of the algorithm used by the integrated function block.

Problems solved by technology

However, in certain cases, the use of a number of independently operating, single-input / single-output control loops is not very effective because the process variables being controlled are affected by more than a single process input and, in fact, each process input may affect the state of many process outputs.

However, in this situation, the operation of the temperature control loop in changing the setting of one of the input valves to control the temperature within the tank may cause the pressure within the tank to increase, which, for example, causes the pressure loop to open the outlet valve to decrease the pressure.

This action may then cause the throughput control loop to close one of the input valves, thereby affecting the temperature and causing the temperature control loop to take some other action.

As will be understood in this example, the single-input / single-output control loops cause the process outputs (in this case, throughput, temperature and pressure) to behave in an unacceptable manner wherein the outputs oscillate without ever reaching a steady state condition.

However, this approach has a tremendous computational burden and is not practically feasible at the current technology level.

Implementation of MPC for such non-square configurations leads to unacceptably poor performance.

This technique, however, is computationally expensive because it applies matrix inversion and can not be use in some cases, like MPC implemented as a function block in a process controller.

Equally important is that some combinations of inputs and outputs of the generated controller may result in an ill-conditioned controller, which results in unacceptable operation.

While conditioning of the controller can be verified and improved when the controller configuration is set up off-line, this task is an excessive burden for on-line operation and is practically impossible to implement at the controller level.

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